Device for evaporating coatings from extremely thin metal elements



H. LASKE 3,188,726

NG COATINGS FROM EXTREMELY June 15, 1965 DEVICE FOR EVAPORATI THIN METAL ELEMENTS Flled May 16, 1962 f a n 7795' EL ECf/FODES 8 .l Mm 1m; W mm 1 n 5 a s E H m a my mwm wa xw s 1 2x a fim w wfifi w a g 5M pa rrm 6 WM ME .w 5 2 am w M w F M V rm M4 m as W United States Patent 3,188,726 DEVKIE F021 EVAPQRATHNG COATEJGS FRUM EXTREMELY THEN METAL ELEMENTS Hans Laske, Luruper Chaussee 73, Hamburg- Altona, Germany Filed May 16, 1962, Ser. No. 195,280 4 Claims. (Cl. 292iitl) The patent proceeds from a process for the manufacture of extremely thin, bright metal wires by drawing with a coating which temporarily enlarges the crosssection and is later removed, the substance used for forming the coating being a substance whose boiling point is lower than that of the drawing material, and the coating being removed by evaporation after completion of the drawing process. (Patent application Ser. No. 114,555 of June 2, 1961).

It is the object of the present invention to improve the process described in application Ser. No. 114,555 and, additionally, to provide an especially simple device with which the extremely thin shaped elements can be manufactured in the form of a strand and further processed.

The process according to the invention, is characterised in that the drawn or rolled-out metal shaped elements are, before the evaporation of the coating, conveyed in the form of a continuous strand through a closed chamber in which, by means of local heating, evaporation of the coating material and, by the arrangement of cooling surfaces, condensation of the evaporated coating material are achieved. The evaporation and condensation of the coating material preferably takes place in vacuo.

A device which is especially suitable for carrying the process according to the invention into eifect contains, between a winding-off and winding-up device, a chamber which is formed with inlet and outlet apertures positioned opposite each other and which, in the immediate vicinity of the strand travelling through, contains a heating device and cooling devices on the chamber walls. During the especially advantageous evaporation in vacuo, the winding-ofi and winding-up device and the evaporation chamber can be surrounded by a housing which is capable of being evacuated.

In order to provide an especially compact evaporation chamber, according to a preferred embodiment of the invention, the walls of the evaporation chamber are designed entirely or partly as a cooling jacket. For heating purposes, a heating coil closely surrounding the strand of material to be subjected to evaporation trea ment is especially suitable.

According to a further special advantage of the inven tion, the evaporated coating material deposited in the chamber can be recovered by the arrangement of removable condensation plates.

Further details and features of the invention will be discussed in the following description of a preferred embodiment which is illustrated by way of example in the accompanying drawings.

FIG. 1 shows diagrammatically, an evaporation chamber arranged within a housing which is adapted to be evacuated, between a winding-off device and a windingup device.

FIG. 2 is a flow sheet of the process.

The device illustrated in the drawings consists of a housing 1 adapted to be sealed otf in air-tight manner and therewith evacuated and which can be connected via a connection 2 with a conventional vacuum pump. Within the housing 1 is a preferably cylindrical evaporation chamber 3 the walls of which are designed as a cooling jacket 4, which is connected via an inlet pipe 5 and an outlet pipe 6 with a coolant circuit. The said coolant 3,188,726 Patented June 15, 1965 circuit, to be connected to the pipes 5 and 6 may be a conventional compression or absorption cooling system.

At two opposite endwalls of the evaporation chamber 3 are two aligned apertures 7 and 8 through which the material to be subjected to evaporation treatment can be supplied to and removed from the evaporation chamber 3. The material, for example a thin, plated wire, which has already been completely drawn and is still covered with a coating facilitating drawing, is stored in the housing 1, on a delivery spool 9, conveyed from there via the apertures '7 and 8 straight through the evaporation chamber 3 and finally again coiled with the aid of the take-up spool 14) also arranged in the housing 1. For driving the wind-oil and wind-up device there is an electric motor disposed in the housing 1; this electric motor is diagrammatically illustrated and designated by the reference numeral 11.

Within the evaporation chamber 3, the wire 12 to be subjected to evaporation is surrounded by a heating coil 13 the connections of which are adapted to be connected in any known manner to a controllable heating circuit.

The device according to the invention operates in the following manner:

The wire provided with the coating for facilitating drawing or any other material used in the form of a continuous strand, is continuously drawn off from the delivery spool 9 and conveyed through the chamber 3 to the take-up spool 16. Since the heating coil 13 within the chamber 3 generates a temperature which is higher than the vaporisation point of the coating facilitating drawing and lower than the melting point of the core of the wire to be subjected to evaporation treatment, the wire coming from the spool 9 loses its coating by evaporation within the chamber 3. The wire from which the coating has been removed leaves the chamber 3 via the aperture 8 and is then again wound on the spool 10. Since the entire housing 2 is evacuated, work can be carried on within the chamber 3 at relatively low temperatures.

The coating material evaporated in the chamber 3 is deposited on the walls of the chamber 3, since the latter are considerably cooled by connection to a cooling system. If, as illustrated in the drawing, removable condensation plates 14 are arranged within the chamber 3,.

it becomes an especially simple matter to recover the evaporated coating material.

The cooling of the chamber 3 is also especially useful in order to keep the starting material on the delivery spool 9 and the final product on the take-up spool 10, including the associated winding devices, cold and efiicient.

The placing of the device for carrying the process according to the invention into effect within an evacuated housing involves no particular expenditure, since the entire arrangement can be kept relatively small and, in view of the thin wire cross-sections, it is unnecessary to replace the spools 9 and 10 very frequently.

As shown diagrammatically in the drawing, the thin metal wire is conducted through an electro-plating bath in which the coating material having a vaporization point substantially lower than the melting point of the wire is deposited on the wire. The coated wire is drawn successively through a number of dies until it is reduced to the desired thickness. The wire is next drawn by means of a winding device through a housing and a closed chamber therein, while an independent heating device in said chamber in the immediate vicinity of the wire evaporates the coating material. The evaporated coating material is condensed on condensation plates in the chamber.

With the process of the invention, it is possible to manufacture extremely fine wires, having cross-sections of less than 7 The dimensions of the final product are exfrom mechanical stressing. A very-considerable advantage relative to the hitherto known processes for manufacturing fine wire consists in that no loss of the mate-l rial substance of the fine wire is incurred during the evaporation process, provided that the physical constants between the core and the encasing material are sufliciently different. 4 V j For carrying the process according to the invention into efiect, it is also important that the temperature in the evaporation 'zone of the chamber 3 and also the vacuum within the housing 1 should be kept as high as possible in. order that the transition of the solid phase of the coating to the gaseous aggregate state may take. place spontaneously.

, Instead of. heatingthe .wire 12 within the chamber by means of a surrounding heating coil.13, it is also possible to. produce an eddy-current flow in the wire 12 by means ofhigh frequency heating acting from the exterior.

' The process according .to the invention is notlimited to wire, but can of course also be extended to any desired other thin, drawn metal shaped elements, such as thin sections, strips andbands.

' What I claim is: V

1-. Apparatus for producing very thin and bright metal wires comprising a Winding-off device for supplying a continuous strand of coated extremely thin metal wire.

havinga predetermined melting point substantially higher I than the evaporation point of. the coating material, a winding-up device opposite to said winding-01f device for taking-up said continuous strand of wire, a closed chamber between said winding-01f device and said winding-up device with small inlet and outletv openings positioned opposite each other for allowing the continuous strand of wire to pass from said winding-off device throughsaid ing device within said chamber in the immediate vicinity of. the strand. passing through for heating said continuous strand beyondthe evaporation point of said coating ma- 2. Apparatus for producing very thin and bright metal wires comprising an evacuated housing, within said housing a winding-E device for supplying a continuous strand of coated extremely thin metal wire having a predetermined melting point substantially higher than the evaporation point of the coating material likewise in said housing a winding-up device opposite to said winding-01f device for taking-up said continuous strand of wire, a closed chamber between said'winding-ofi device and said winding-up device with small inlet and outlet openings positioned opposite each other for allowing the continuous strand of wire to pass from said winding-off device through'fsaid chamber to said winding-up device, an independent heating device within said chamber in the immediate vicinity of the strand passing throughfor heating said continuous strand beyond the evaporation point of said coating material; cooling surfaces in said chamber adjacent to its walls for condensingthe evaporated coating material and removable condensation plates mounted adjacent said walls for recovering the evaporated coating material, V v i 3.The'invention as claimed in claim 2, wherein the walls of the evaporation chamber are designed as a cooling jacket.

chamber to said winding-up device, an independent heatstrand material to besubjected to evaporation treatment.

7 References Cited by the Examiner UNITED STATES PATENTS 930,723 8/09 'Von Bolt-on et al 29-198 X "1,071,174 8/13 Von Pirani 205-21 1,273,506 7/18 Lederer 205-21 1,345,441 7/20 Hisamoto 205-21 1,958,468 5/34 Christie et al. 29-529 2,100,697 11/37 Loewe 219-10.41 X 1 2,302,357 11/42 Thornton 219-19 2,476,151 *7/49 Le Ieune 29-529.

2,447,979 8/48 Hensel et al. 2,520,494 8/50 Dalin 219-19 2,879,739 3/59 Bugbee et al. 117-1071 X 2,930,879 3/60 Scatchard 219-19 WHITMOREA. WILTZ, Primary Examiner,

JOHN F. CAMPBELL, Examiner. 

1. APPARATUS FOR PRODUCING VERY THIN AND BRIGHT METAL WIRES COMPRISING A WINDING-OFF DEVICE FOR SUPPLYING A CONTINUOUS STRAND OF COATED EXTREMELY THIN METAL WIRE HAVING A PREDETERMINED MELTING POINT SUBSTANTIALLY HIGHER THAN THE EVAPORATION POINT OF THE COATING MATERIAL, A WINDING-UP DEVICE OPPOSITE TO SAID WINDING-OFF DEVICE FOR TAKING-UP SAID CONTINUOUS STRAND OF WIRE, A CLOSED CHAMBER BETWEEN SAID WINDING-OFF DEVICE AND SAID WINDING -UP DEVICE WITH SMALL INLET AND OUTLET OPENINGS POSITIONED OPPOSITE EACH OTHER FOR ALLOWING THE CONTINUOUS STRAND OF WIRE TO PASS FROM SAID WINDING-OFF DEVICE THROUGH SAID CHAMBER TO SAID WINDING-UP DIVEIE,AN INDEPENDENT HEATING DEVICE WITHIN SAID CHAMBER IN THE IMMEDIATE VICINTIY OF THE STRAND PASSING THROUGH FOR HEATING SAID CONTINUOUS STRAND BEYOND THE EVAPORTION POINT OF SAID COATING MATERIAL; COOLING SURFACES INSAID CHAMBER ADJACENT TO ITS WALLS FOR CONDENSING THE EVAPORTATED COATING MATERIAL AND REMOVABLE CONDENSATION PLATES MOUNTED ADJACENT SAID WALLS, FOR RECOVERING THE EVAPORATED COATING MATERIAL. 